8Cd Comparing gas exchange
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Gas Exchange in Different Organisms
All living organisms need a way to exchange gases with their environment. This process is essential for respiration, which provides energy for life processes. Different organisms have evolved different gas exchange systems, but they all share common features to allow efficient diffusion of gases such as oxygen and carbon dioxide.
Common Features of Gas Exchange Systems
Although these gas exchange systems are found in different organisms, they share important similarities:
- Large Surface Area – This increases the amount of gas that can diffuse at one time.
- Thin Surfaces – A short diffusion distance allows gases to move quickly.
- Steep Concentration Gradient – Maintained by blood flow in animals or air circulation in plants, ensuring efficient diffusion.
Gas Exchange in Humans
Humans and other mammals have lungs, which contain millions of tiny air sacs called alveoli. These alveoli provide a large surface area for gas exchange. Oxygen from the air we breathe in diffuses across the thin walls of the alveoli into the blood, while carbon dioxide diffuses out of the blood into the alveoli to be exhaled. The alveoli have very thin walls, only one cell thick, ensuring a short diffusion path for gases to move quickly between the lungs and the blood. Additionally, they are surrounded by a dense network of capillaries, which maintain a steep concentration gradient by constantly bringing in blood with low oxygen levels and removing oxygenated blood.
